21742031 has 16 divisors (see below), whose sum is σ = 23911200. Its totient is φ = 19688448.

The previous prime is 21742027. The next prime is 21742033. The reversal of 21742031 is 13024712.

It is not a de Polignac number, because 21742031 - 2² = 21742027 is a prime.

It is a super-2 number, since 2×21742031² = 945431824009922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21741994 and 21742012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21742033) 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, 52955 + ... + 53363.

It is an arithmetic number, because the mean of its divisors is an integer number (1494450).

Almost surely, 2^21742031 is an apocalyptic number.

21742031 is a deficient number, since it is larger than the sum of its proper divisors (2169169).

21742031 is a wasteful number, since it uses less digits than its factorization.

21742031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 538.

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 21742031 is about 4662.8350817931. The cubic root of 21742031 is about 279.1044131576.

Adding to 21742031 its reverse (13024712), we get a palindrome (34766743).

The spelling of 21742031 in words is "twenty-one million, seven hundred forty-two thousand, thirty-one".