697540921 has 27 divisors (see below), whose sum is σ = 894504933. Its totient is φ = 543538380.

The previous prime is 697540853. The next prime is 697540931. The reversal of 697540921 is 129045796.

It is a happy number.

The square root of 697540921 is 26411.

It is a perfect power (a square), and thus also a powerful number.

It is a de Polignac number, because none of the positive numbers 2^k-697540921 is a prime.

It is not an unprimeable number, because it can be changed into a prime (697540931) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 63412806 + ... + 63412816.

Almost surely, 2^697540921 is an apocalyptic number.

697540921 is the 26411-st square number.

697540921 is the 13206-th centered octagonal number.

It is an amenable number.

697540921 is a deficient number, since it is larger than the sum of its proper divisors (196964012).

697540921 is an frugal number, since it uses more digits than its factorization.

697540921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78 (or 18 counting only the distinct ones).

The product of its (nonzero) digits is 136080, while the sum is 43.

The cubic root of 697540921 is about 886.8630551443.

The spelling of 697540921 in words is "six hundred ninety-seven million, five hundred forty thousand, nine hundred twenty-one".