21271969 has 2 divisors, whose sum is σ = 21271970. Its totient is φ = 21271968.

The previous prime is 21271961. The next prime is 21271973. The reversal of 21271969 is 96917212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12510369 + 8761600 = 3537^2 + 2960^2 .

It is a cyclic number.

It is not a de Polignac number, because 21271969 - 2³ = 21271961 is a prime.

It is a super-2 number, since 2×21271969² = 904993330273922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21271961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10635984 + 10635985.

It is an arithmetic number, because the mean of its divisors is an integer number (10635985).

Almost surely, 2^21271969 is an apocalyptic number.

It is an amenable number.

21271969 is a deficient number, since it is larger than the sum of its proper divisors (1).

21271969 is an equidigital number, since it uses as much as digits as its factorization.

21271969 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13608, while the sum is 37.

The square root of 21271969 is about 4612.1544857041. The cubic root of 21271969 is about 277.0783315333.

It can be divided in two parts, 2127 and 1969, that added together give a 12-th power (4096 = 2¹²).

The spelling of 21271969 in words is "twenty-one million, two hundred seventy-one thousand, nine hundred sixty-nine".