1661557031 has 2 divisors, whose sum is σ = 1661557032. Its totient is φ = 1661557030.

The previous prime is 1661556991. The next prime is 1661557043. The reversal of 1661557031 is 1307551661.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1661557031 is a prime.

It is a super-2 number, since 2×1661557031² = 5521543534531069922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1661556982 and 1661557000.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1661557061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830778515 + 830778516.

It is an arithmetic number, because the mean of its divisors is an integer number (830778516).

Almost surely, 2^1661557031 is an apocalyptic number.

1661557031 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661557031 is an equidigital number, since it uses as much as digits as its factorization.

1661557031 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18900, while the sum is 35.

The square root of 1661557031 is about 40762.2010077964. The cubic root of 1661557031 is about 1184.4182325946.

The spelling of 1661557031 in words is "one billion, six hundred sixty-one million, five hundred fifty-seven thousand, thirty-one".