21623797 has 16 divisors (see below), whose sum is σ = 24127488. Its totient is φ = 19252800.

The previous prime is 21623773. The next prime is 21623803. The reversal of 21623797 is 79732612.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21623797 is a prime.

It is a super-3 number, since 3×21623797³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21623897) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 56268 + ... + 56650.

It is an arithmetic number, because the mean of its divisors is an integer number (1507968).

Almost surely, 2^21623797 is an apocalyptic number.

It is an amenable number.

21623797 is a deficient number, since it is larger than the sum of its proper divisors (2503691).

21623797 is a wasteful number, since it uses less digits than its factorization.

21623797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 540.

The product of its digits is 31752, while the sum is 37.

The square root of 21623797 is about 4650.1394602743. The cubic root of 21623797 is about 278.5975664526.

The spelling of 21623797 in words is "twenty-one million, six hundred twenty-three thousand, seven hundred ninety-seven".