21770993 has 2 divisors, whose sum is σ = 21770994. Its totient is φ = 21770992.

The previous prime is 21770989. The next prime is 21771019. The reversal of 21770993 is 39907712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11607649 + 10163344 = 3407^2 + 3188^2 .

It is a cyclic number.

It is not a de Polignac number, because 21770993 - 2² = 21770989 is a prime.

It is a super-2 number, since 2×21770993² = 947952272412098, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21770953) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10885496 + 10885497.

It is an arithmetic number, because the mean of its divisors is an integer number (10885497).

Almost surely, 2^21770993 is an apocalyptic number.

It is an amenable number.

21770993 is a deficient number, since it is larger than the sum of its proper divisors (1).

21770993 is an equidigital number, since it uses as much as digits as its factorization.

21770993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23814, while the sum is 38.

The square root of 21770993 is about 4665.9396695628. The cubic root of 21770993 is about 279.2282874394.

The spelling of 21770993 in words is "twenty-one million, seven hundred seventy thousand, nine hundred ninety-three".